Sennheiser lavaliere interruption

[John Willett]

Originally Posted by Les Wilson

Wish this thread had a "Like" button..... anyway, how does all this work with plugon transmitters? I use one from my sound guy's mixer to my camera. Is there a preferred orientation for the antenna on my receiver for a plugon?

The antenna of a plug-on will tend to have slant polarisation and could move from horizontal to vertical.

The best is to put the receiver antennas as a "V" as I suggested above with an angle between them of about 90°.

[Paul R Johnson]

Just a thought - years ago, we used to use aerial combining for point to point links to squeeze an extra 3dB. Using a short matching length of coax in a small housing. Just kept impedance at the correct 50Ohms, yet allowed extra gain.

It occurred to me that John's classic V compromise to allow for polarisation shifts could be paralleled in this way, then another identical one fed from the other aerial socket to a remote position. This would provide better protection from nulls, yet cope better with polarisation shifts. AND - it wouldn't cost very much.

As a quarter wave working without a proper ground plane isn't really a proper 50Ohm match, you'd probably want to use dipoles in an 'X' formation, but I've not heard of anyone trying this. I've never liked paddles very much, as log periodics, especially short ones don't really make much sense unless they're the right distance away as the polar pattern on a smaller stage makes placement critical. You often see them pointed from the wings, straight across the stage, but this wastes the audience side of the pattern, and can offer dead spots upstage.

We started with a 'fault' that could have been all sorts, got it tracked down to RF issues, and are now etting quite deep. Ironically, the G3, with dangly output cable might well offer the best out of the box solution to polarisation issues.

What is certain is that the worse case must be this:
http://www.thecameraclass.com.au/ima.../SonyZ7P13.jpg

[Tim Polster]

Hey guys,

I know I am late ot the party, but I would like to get some recommendations for better wireless systems that are less prone to this interference.

I have had a couple Senn. 100 systems which are now illegal and they have always suffered from this Phut, pzzzt behavior. I try to keep the aerials upright but it always seems to happen during live events where you can not stop and go change something.

It does seem like distance plays a part and the distance on these mics seems to be a lot sharter for perfect operation than we typically use them.

So, I was wondering if you could advise from personal experience which system would be an improvement in range and reliability of signal.

Thanks for your input.

[Rick Reineke]

Your system is likely not set-up properly. Have you checked and avoided TV station frequencies in your area and done a scan prior to shooting.
An occasional RF hit is common to all wireless systems. Lectro, Zaxcom are more bullet-proof but cost 3x that of the G2/3 systems and increased range would not be by much if at all.. if fact, some tests indicate further range than the $3k Lectro systems.
Multi-path dropouts can be reduced by using a diversity system. The G3 is a diversity system, the G2 is not.

[John Willett]

Originally Posted by Tim Polster

Hey guys,

I know I am late ot the party, but I would like to get some recommendations for better wireless systems that are less prone to this interference.

I have had a couple Senn. 100 systems which are now illegal and they have always suffered from this Phut, pzzzt behavior. I try to keep the aerials upright but it always seems to happen during live events where you can not stop and go change something.

It does seem like distance plays a part and the distance on these mics seems to be a lot sharter for perfect operation than we typically use them.

So, I was wondering if you could advise from personal experience which system would be an improvement in range and reliability of signal.

Thanks for your input.

The problem is not the Sennheiser, it's the frequency you have chosen and how you have set it up.

Try and keep the antenna off the body - if the transmitter antenna touches the body you will attenuate the signal by as much as about 70dB! Even a short distance off the body improves transmission amazingly.

This will be true for all radiomic. transmitters, not just Sennheiser.

Your problem sounds like either what I have described above and/or you have chosen a frequency too close to another/more powerful transmitter which is causing interference.

You should get a good 100m range with evolution systems and maybe mote (depending on the receive antennas used and how you have set them up).

I have had three-quarters of a mile range on a Sennheiser system with good antennas.

[Colin McDonald]

I knew I had posted before about how far the Sennheisers can reach under ideal conditions, but it took me a while to find it: post #7 in this thread

[Tim Polster]

Thanks for your reply. It is tough to get the transmitter away from the body when a person needs to wear it! I try to have folks put it in pockets if possible, but they want to hide it.

The trouble with choosing a frequency is that the interruptions are random in nature. So you can set the thing up, go live then the "stuff" happens. How does one know these things?

[Colin McDonald]

I found Potential for LTE interference to Wireless Audio Report (OFCOM) interesting reading, but it is obviously targeted at the UK situation with the dreaded 'Digital Switchover' and the introduction of 4G. Pity it doesn't name the brands and models tested, but it does seem to indicate that you get what you pay for to some extent.

[John Willett]

Originally Posted by Tim Polster

Thanks for your reply. It is tough to get the transmitter away from the body when a person needs to wear it! I try to have folks put it in pockets if possible, but they want to hide it.

The trouble with choosing a frequency is that the interruptions are random in nature. So you can set the thing up, go live then the "stuff" happens. How does one know these things?

It's not the transmitter that has to be away from the body, but the antenna.

A good way with the Sennheiser systems is to reverse the belt clip and mount them with the connections pointing down. Clipped to the belt this often holds the antenna off the body.

Also, make sure you put the mic. on properly, hide the cable underneath the clothes, etc., and not just leave it all hanging.

[Paul R Johnson]

On radio systems everything conspires against you. We're talking low power, very inefficient aewrial systems both ends of the chain, and proximity to sponges that soak up RF energy - as in people! In clear space, as John says, distance can be pretty remarkable, but equally I find getting it to cross an 8m stage intact can be quite a challenge. Diversity receivers can help, but in many cases, the benefit of these is only evident when the receiver aerials can be some distance apart. Very rarely is distance the real issue, because a quick look at the signal strength meters shows that they usually sit on either maximum or zero. The two feet of travel that the wearer needs to do can slam it from full strength to zero in one pace, and you only know where the null is when it happens. If you watch the Grand Prix you see people with their radio systems aerials on their headsets, up in the air, clear of obstacles and the improvement is pretty drastic. With packs in a pocket, pressed up against a body, instead of omni directional output, up to 180 degrees has to go through a body. add in more loss from angle mismatches between TX and RX aerial polarisation and it's a wonder we ever get them to work. In my theatre work, where budgets are always tight, we still find the money for somebody to look after radio mics - because they're that much trouble. Batteries, dodgy cables, dodgy mic placement, RF issues, the problems go on and on.

[Greg Miller]

Originally Posted by John Willett

Also, make sure you put the mic. on properly, hide the cable underneath the clothes, etc., and not just leave it all hanging.

That's an important point, and seldom mentioned. The shield on the mic wire will absorb a lot of the RF, if it is located next to the antenna wire! So while the antenna wire hangs down vertically (hopefully a few inches away from the body), the mic wire needs to be carefully positioned away from the antenna! For example, dress it immediately away from the transmitter, horizontally along the belt, and hold it in place with a few tabs of tape. If there's excess, coil it loosely elsewhere, not in close proximity to the antenna.

[Tim Polster]

Good information, thank you. I need to pay more attention to this and take a little more charge of how the mic is worn. So often I am putting these things on people who are not professionals or actors and they are quite uncomfortable with the whole thing. My first thought is getting proper mic placement but now I will put equal effort into "rigging" the transmitter, antenna and wire.

[Tim Polster]

I still would like to explore a better wireless setup than what I have now. Any recommendations for a three peice setup? (trans., rec. & handheld)

What would really be useful to me is if I could get a system that would allow me to plug into a mixing board and send a line level signal to my camera. Or at least a way to accept the board signal and get it to my camera with a strong signal.

Thanks for your input.

[Dave Partington]

Also late to the party here.... but I have an additional question.

We have a couple of G2 systems and one G3 system. The G3 has never given us a moment's problem, even when the XMIT is vertical and the Receiver was horizontal, but I do understand why they should both be the same.

The G2s have not been so lucky. We have one system that's a little more flakey than the other and is more likely to give us the phut phut kind of interruption even when everything is mounted vertically. We've even run the two receivers in to the same recorder when receiving from the same transmitter and the same one each time has the problem while the other one is perfect.

However, I've noticed that over time the arials are no longer 'straight'. They've developed their own curved shape. It's not huge, but they are certainly not 'straight'. How much difference will that make and is there some neat method I'm not aware of to make/keep them straight (if it actually makes a difference) ?

[Brian P. Reynolds]

The G3s' are diversity and the G2s' are NON-divesity that makes a HUGE difference for the RX units.